The present invention relates to electromagnetic properties of layered materials (such as thin films situated upon substrates), more particularly to methods and apparatuses for determining the resistance of such materials.
Techniques are known for measuring reflection, transmission and absorption of electromagnetic radiation by an object (e.g., thin film) that is layered upon a substrate. Various approaches have been conventionally taken for quantifying these properties as a function of the frequency of the electromagnetic radiation that impinges upon the object.
In contrast, the quantification of the resistance of a thin film as a function of frequency has been problematical. Four-point probe and other methodologies are known for measuring the resistance of a thin film. Four-point probe methodology, however, only produces a single value at dc and does not manifest the effects of frequency. An inverse transform of transmission data has been used to quantify the resistance of a thin film as a function of frequency, but this methodology is complicated.